A post by Andy
{Modified the title theme some. We think of ourselves much more as a big van than a small RV. I now want to start prefacing this and future posts to be more representative of our self-image.}
So, to the meat of the subject. I just finished our hood scoops! Why did I make hood scoops? Well, for one, they look pretty cool and I needed a prominent place to put my new go-fast emblems that I ordered from Amazon.
Mainly, we are trying to get as much power out of the engine so we can get our heavy old self up the high steep hills. In that vein, I have been playing with the spark timing, carb mixture, and intake airflow. By tweaking and adjusting these parameters we are working to get the most power and efficiency out of our old engine. Specifically, advancing the timing can get the engine to produce more power, but too much spark advance causes engine problems—pinging and preignition. If the engine is cooler, one can run with more advance. Another way to look at it is that with a given timing advance, if the engine and intake air get hotter, then the timing is too far advanced.
Maybe a side note about my “go-fast” emblems. Car companies try to sell cars. Sometime fancy cars come with racing stripes, cool graphics, and badges on the side about engine stuff. A joke among car people is the question “How much horsepower do the stripes add?” The answer is, of course, none. But… they do look cool. Look around, they are everywhere: M3, AMG, Hemi, 440, HiPo. The only thing the badge or stripes could actually do is add an immeasurably small increase in drag, or some unneeded paint weight. They are simply for the people in the car next to you. All the same, they look sporty, so I bought some that state the displacement of our engine and say it is “High Performance”. What I’m saying here is they do nothing, but they truly do look great!
So, I wanted more air to get in and out of the engine compartment to cool the engine, and have the air flowing into the air cleaner be as cool (and dense) as possible. To make sure I had an understanding of the pre-hood-scoop environment, I first taped the probe end of my digital temperature gauge to the air cleaner. Over a few weeks in different driving conditions and different altitudes, we took notes about the temperature measurements of the air cleaner and air filter. You can see the wire to the probe, and the tape holding it in one location.
Overall, we are in the 150º–160ºF range under the hood after the engine gets warmed up and when the ambient temperature is in the 70º–80ºF range. So, to get more outside air in and more inside air out we need some kind of venting. I looked online, and $50+ plastic vents and scoops can be found, but they were not really van-sized, and seem flimsy. Metal ones can also be found, but are more expensive, and again, really don’t fit. Apparently there is an untapped market of people who want to mod 1985 Ford vans! (Investors be wary—the market may be small.) I finally hit on the idea that rectangle cake pans are about the size I wanted, and they are inexpensive, and they are made of metal designed to withstand 500ºF+. Going with this thought, while we were camping in El Malpais National Monument, I made some cake pan-sized cardboard mockups and spray painted them with a blue that I had.
Test fitting…
I thought that looked good, so a few days later when we were in a town, we got some cake pans.
One morning, a few weeks later, when we where camping at the Great Salt Lake, I got out the pans, tin snips, sandpaper, and primer, and got to work remaking our sweet cake pans into even sweeter performance hood scoops (please note the word play).
Here they are.
Test fitting.
We stashed them away for a bit and traveled onward. Another week later we had a free day while visiting our friends the Higdems in Kimberly, ID. I measured, moved, marked, measured, and measured and marked again. Then I started drilling holes in the hood.
Lots of little holes now!
After fitting and drilling the mounting holes, I now knew what piece of the hood (bonnet, for any Brits out there) to cut out. Out with the jig saw.
Another side note here: When putting the Turtle together, we set ourselves up with a few DeWalt cordless tools and the battery charger that plugs into a 12V cigarette lighter. The tool charger is now wired to our solar-charged batteries, so we are using the sun’s energy to drill, cut, and modify our hood. It feels fun to know that when working on projects such as this!
For the final install, I put down a small bead of RTV sealant, aligned the scoops, and screwed in the 6 screws per scoop that I had already pre-drilled. After the RTV cured a bit, I got out our boat paint and went at it.
Included above is, obviously, a photo of what Scout and Gracie were doing at the time. A few days later, at Dave and Ryann’s place, I added more RTV to smooth the transition and put on more paint to finish it all off.
All finished now, after the last painting and with the great go-fast badges installed.
We should call this the conclusions section of the post, for you science people out there. Well, they have been on now for a week, and we don’t move fast, so we have only driven a few hundred miles. We will need to collect more data, but so far the maximum under-hood temperature we have seen in 135ºF, and most of the time it has been in the 100º-120ºF range (and we are actually in hotter weather than when we took our non-hood scoop measurements). We have also driven through crazy heavy rain and, as expected and hoped for, the small amount of water that enters through the scoops has no adverse effects on the engine. Generally, a pretty solid success, and I have since advanced the ignition timing just a bit with no pinging.
Oh, maybe a cost breakdown. The sum total of the cake pans, primer, quantity of screws, RTV, and paint used is less than $20. The go-fast badges were $11 each. Dave suggests I sell it as “The whole project was less than 45 dollars.” I think I shall adopt that tract!
All that for less than 45 dollars!!!
Blue Turtle Crossing 